The present invention relates to a data communication apparatus and a data communication method, which shortens the time needed for a previous-procedure to be performed prior to data communication using a modem, such as facsimile communication.
Recently, in data communication apparatus, data communication using a V.34 modem (33.6 kbps), which is conformed to recommends of the ITU-T. The ITU-T also recommends T30 ANEXF (so-called Super G3) as facsimile communication standards using the V.34 modem for facsimile apparatuses. A previous-procedure for facsimile communication is carried out according to the standards procedure, after which communication of image data is executed.
Such a communication protocol will be explained based on the sequence chart illustrated in FIG. 1. FIG. 1 is a control signal view for a communication protocol for facsimile communication according to prior art.
Referring to FIG. 1, reference character 19a denotes a communication procedure for selecting a modulation mode from among a V34 half-duplex, V34 full duplex, V17 half-duplex, etc. Reference character 19b denotes a communication procedure for line probing to check a line and determine various kinds of parameters. Reference character 19c denotes a communication procedure for modem training. Reference character 19d denotes a communication procedure for setting a modem parameter. Reference character 19e denotes a communication procedure for exchanging a facsimile control signal. And, reference character 19f denotes a data communication procedure for the primary channel. The upper side in the diagram is a sequence for a caller modem, and the lower side is a sequence on an answer modem, and the sequences progress from left to right.
The above communication protocols will be specifically described as follows:
First, in the communication procedure 19a for selecting a modulation mode, the selection of a modulation mode and communication procedure, which permit communication between a caller modem and an answer modem, through a V.21 modem (300 bps, full-duplex), is carried out after a line connection is established. A facsimile apparatus using a V.34 modem selects a V.34 modem as the modulation mode and facsimile communication as a communication procedure.
After that, in the communication procedure 19b for line probing, the caller modem transmits a line probing tone. The line probing tone is received by the answer modem, a line inspection is carried out, and a training parameter is selected based on the result of the line inspection.
In the communication procedure 19c for modem training, the caller modem sends training signals based on the training parameter selected under the line probing communication procedure 19b, while the answer modem receives the training signals, learns a filter coefficient for an adaptive equalizer for compensating the line characteristic and checks the reception quality of the training signals.
In the communication procedure 19d for selecting a modem parameter, modem parameters are negotiated between the caller modem and the answer modem in full-duplex communication at 1200 bps. As a result, an optimal modem parameter is selected from the modem parameters preset in the apparatus, the result of the line inspection and the inspection of the reception quality of the training signals.
In the communication procedure 19e for a facsimile control signal, negotiation of facsimile control signals NSF, CSI, DIS, TSI, DCS, CFR, etc. is executed in full duplex communication at 1200 bps.
Then, in the data communication procedure 19f, image data is transmitted from the caller: modem in half-duplex communication at 2400 bps to 33.6 kbps. Image data is received by the answer modem. In the case of performing communication at the maximum communication rate of 33.6 kbps, image data can transmit in approximately three seconds per a sheet of paper of size A4.
The caller and answer modes, which execute the aforementioned communication protocol, carry out communication in accordance with the training parameter selected under the communication procedure 19b for communication line probing and the modem parameter selected under the communication procedure 19d for selection of a modem parameter. To compensate the line characteristic, the receiver modem executes communication using the filter coefficient that has learned in the modem training 19b. This ensures optimal data communication according to the line quality.
However, the above-described prior art structure involves five channels of a procedure before starting sending image data after line establishment, and thus requires about 7 seconds. By contrast, since electric transmission of a single sheet of image data at the maximum communication rate of 33.6 kbps takes about 3 seconds, the procedures requires over 60% of the entire time of 11 seconds required for transmission of one sheet of an original including the later-procedure about 1 second. This time needed for the previous-procedure gets greater as the number of transmission/reception lines increases, and generates wasteful time and communication cost.
In consideration of the above-mentioned problems, an object of the present invention is to provide a data communication apparatus which can shorten time for setting various kinds of parameters of a modem and time for a previous-procedure including time for modem training before the image transmission.
Also, an object of the present invention is to provide a data communication apparatus such that a supported short previous-procedure function appropriately operates even when a communication error rate is high or line characteristics are changed.
More specifically, there is provided a data communication apparatus comprising:
storing means for storing various kinds of modem control information for each destination in association with an operation key;
calling means for generating a call to said destination by a transmission command from said operation key to start communication; and
communication control means for transmitting a shift notify signal indicative of the shift to a previous-procedure for short communication in a case of communication using said calling means, thereafter controlling the modem based on said various kinds of control information so as to shorten a previous-procedure and carry out data transmission.
The data communication apparatus according to the first aspect of the present invention comprise storing means for storing various kinds of modem control information for each destination in associate with an operation key;
calling means for generating a call to said destination by a transmission command from said operation key to start communication; and
communication control means for transmitting a shift notify signal indicative of a shift to a short previous-procedure in a case of communication using said calling means, thereafter controlling the modem based on said various kinds of control information so as to shorten a previous-procedure and carry out data transmission.
According to the above-mentioned structure, communication to the destination registered in the operation key is executed in the short previous-procedure based on control information stored in storing means, so that an operator can shorten communication time by considerably simple operation. Since it is unnecessary to obtain modem control information suitable for the destination by communication in the previous-procedure, time required for a previous-procedure can be greatly shortened. Control information described here is time for modem parameter or modem training.
The second aspect of the present invention, in the data communication apparatus of the first aspect, the communication control means transmits the shift notification signal that indicates shift to a short previous-procedure in place of a calling menu signal, in response to a deformed answer signal from an answer side apparatus with respect to a calling signal transmitted in previous-procedure configured to conform to Recommendation ITU/V.34 dated September 1994.
According to the above-described structure, the apparatus in answer side receives either the calling menu signal in V.34 protocol or the shift notify signal indicating shift to the short previous-procedure. Since the apparatus has only to identify these signals, the apparatus can receive the shift notify signal to the short previous-procedure without requiring a greatly change in a receiving signal processing circuit.
The third aspect of the present invention, in the data communication apparatus of the first or second aspect, the communication control means confirms whether or not various kinds of the modem control information are stored in said storing means prior to the shift to the short previous-procedure, and executes the short previous-procedure only when said control information is stored.
According to the above-mentioned structure, control of communication control means can be simply carried out. Namely, communication control means check a writing state of storing means, and select whether or not control information is written to storing means, so that communication control means may change the ON/OFF state of short previous-procedure, easily.
The forth aspect of the present invention, in the data communication apparatus of the first or second aspect, the data communication apparatus farther comprises parameter registering means for storing various kinds of the modem control information obtained in the previous-procedure executed with respect to the destination registered in said storing means in a state that only destination information corresponding to said operation key is stored in said storing means.
According to the above-described structure, if the destination information has only to be registered correspond to the operation key, control information actually obtained in communication with the destination in the normal previous-procedure is automatically stored, and subsequent communication can be automatically executed in the short previous-procedure. Therefore, this gives a good operability to the operator.
Destination information described here is one that specifies the destination such as a destination""s name, a telephone number, ID information.
The fifth aspect of the present invention, the data communication apparatus of the forth aspect, the apparatus further comprises error detecting means for detecting an error of communication, and the parameter registering means does not execute the registration of control information when error detecting means detects an error in the previous-procedure for registering the parameter for short previous-procedure.
The above-described parameter registering means in the fifth aspect automatically registers various kinds of the modem control information obtained in the previous-procedure. However, if control information in the previous-procedure where a error has been occurred is registered, there is a high possibility that an error will occur again. For this reason, registration of control information is not carried out. Since the short previous-procedure is not executed in next communication, there can be avoided a case in which communication time is increased due to the short previous-procedure execution error.
The six aspect of the present invention, in the data communication apparatus of the fifth aspect, the parameter registering means executes once stores control information obtained in the normal previous-procedure in said storing means, after which said control information is erased, thereby executing processing in which no registration of control information is carried out.
According to the above-mentioned structure, since processing for prohibiting registration of parameter (control information) to be carried out first and processing for erasing control information registered in storing means can be executed in the same processing flow, simplification of processing and software can be improved.
The seven aspect of the present invention, the data communication apparatus of one to six aspect, when the short previous-procedure proceeds, abnormally, said communication control means performs a shift to communication by the normal previous-procedure or second communication procedure having low communication speed so as to continue communication after a lapse of a predetermined period of time.
According to the above-mentioned structure, when the short previous-procedure does not normally proceed within a predetermined period of time, communication in the other communication procedure whose communication speed is low is continued. For this reason, there can be avoided a case in which a communication error occurs by failure in the short procedure. In this case, the communication protocol to be shifted may be a communication protocol whose communication speed is the same as that of the short previous-procedure execution time or a communication protocol whose communication speed is lower than that of the short previous-procedure execution time.
The eight aspect of the present invention, the data communication apparatus of the seven aspect, the second communication procedure is a communication protocol according to Recommendation ITU/T.30, dated 1976 and the predetermined period is time for which NSF/CSI/DIS signals of T.30 can be received twice or more after shift to the second communication procedure.
According to the above-mentioned structure, in the case of failure in the short previous-procedure, shift to T.30 communication procedure is carried out, and a standby state for a control signal of 300 bps is set. NSF/CSI/DIS signals are repeatedly transmitted. For this reason, even if first reception of a control signal ends in failure, at least two signal reception times can be ensured not to generate a communication error. Therefore, even if the apparatus on the destination is changed to one, which is not equipped with the short previous-procedure, or the short previous-procedure ends in failure, shift to T.30 protocol can be surely executed.
The nine aspect of the present invention, the data communication apparatus of the one to six aspect, when the short previous-procedure does not proceeds normally, the communication control means change the procedure from the short previous-procedure to a second communication procedure having low communication speed so as to continue communication after the number of retrial times of said short previous-procedure reaches a fixed value.
Although the shift to the second communication procedure was executed after a lapses of a predetermined period of time in the seven aspect, the shift to the second communication procedure is executed by the number of retrials of the short previous-procedure in the nine aspect.
The ten aspect of the present invention, in the data communication apparatus of the one to fourth aspect, the apparatus further comprises error detecting means for detecting an error of communication, wherein when said error detecting means detects an error after starting execution of the short previous-procedure, said communication control means maintains destination information stored in said storing means on one hand and erases only the corresponding various kinds of control information in said storing means on the other hand.
In other words, if some error occurs after the start of executing the short previous-procedure and control information used at this time is used in the future, there is a high possibility that an error will occur again. For this reason, such information is erased. Such communication error occurring after the start of executing the short previous-procedure can be applied to both a case in which the previous-procedure is executing and a case in which data communication is executing after the previous-procedure is accomplished. However, treatment of control information thereafter differs, depending on whether or not the short previous-procedure is ended
The eleven aspect of the present invention, in the data communication apparatus of the seven aspect, the apparatus further comprises parameter registering means for executing a normal previous-procedure in the same call so as to newly store various kinds of the modem control information obtained in the executed normal previous-procedure in said storing means when the short previous-procedure does not proceeds normally.
According to the above-mentioned structure, control information stored in storing means is automatically updated in the same call. Therefore, next communication is started in the short previous-procedure. There is a case in which an error occurs again based on updated control information. However, if such occurrence of error is repeated, the execution of the short previous-procedure itself is prohibited as described later.
The twelve aspect of the present invention, in the data communication apparatus of the ten aspect, the error detecting means determines an error of communication when a data transmission error rate of communication obtained after executing the short previous-procedure or the normal communication previous-procedure increases to a predetermined value or more.
According to the above-described structure, for example, when the error gradually increases during communication, control information registered in storing means is determined as an unsuitable parameter. This is particularly useful for a case in which line characteristic is better than a normal case at a parameter registration time.
The thirteen aspect of the present invention, in the data communication apparatus of the ten aspect, the error detecting means determines an error of communication when a data transmission error rate of communication obtained after executing the short previous-procedure or the normal previous-procedure is lower than a data transmission error rate of a communication protocol whose speed is slower than communication speed.
According to the above-described structure, there can be avoided a disadvantage in which communication is repeated at communication speed which is lower than the normal communication speed. In contrast to the previous case, this is particularly useful for a case in which line characteristic is worse than a normal case at a parameter registration time.
The fourteen aspect of the present invention, in the data communication apparatus of the twelve aspect or thirteen aspect, the apparatus further comprises parameter registering means for storing various kinds of the modem control information obtained in a next normal previous-procedure executed with respect to the destination in said storing means after erasing control information from said storing means.
According to the above-mentioned structure, next communication is executed in the normal previous-procedure. At this time, registration of modem control information is automatically performed, and next communication is automatically executed in the short previous-procedure.
The fifteen aspect of the present invention, in the data communication apparatus of the first to fourth aspect, when the number of error generations of the short previous-procedure or an error rate to the number of short previous-procedure executions exceeds a predetermined value, the short previous-procedure with respect to the destination,in subsequent communication is prohibited from being executed.
According to the above-mentioned structure, there can be avoided a case in which the short previous-procedure is executed in accordance with control information having a high error rate to generate an error repeatedly. The error rate may be calculated at the time when the short previous-procedure execution time reaches a predetermined value, or the number of errors may be simply counted. When the error rate is high, the execution of the short previous-procedure is prohibited at the earliest time, so that the number of times of executing waste short previous-procedure can be reduced.
To count the number of errors, as described in aspect sixteen, the apparatus comprises an error counter for counting a number of error generations of short previous-procedure, wherein said error counter counts up every time when various kinds of control information stored in said storing means are erased.
The seventeen aspect of the present invention, in the data communication apparatus of the sixteen aspect, the error counter determines whether or not communication is one that is started in the short previous-procedure before counting up, and the error counter executes no counting operation when a result of said determination is no.
According to the above-mentioned structure, the error counter can surely perform the counting operation. Particularly, in a case where control information is erased from storing means in the normal communication protocol as described in aspect ten, the counting operation of the error counter is prohibited, so that no error occurs in the count value.
The eighteen aspect of the present invention, in the data communication apparatus of the fifteen aspect, the communication control means confirms whether or not various kinds of the modem control information are registrable in said storing means prior to the shift to the short previous-procedure, and executes no short previous-procedure when various kinds of the modem control information are non-registrable.
According to the above-described structure, when the error often occurs in the short previous-procedure, registration of control information to storing means is prohibited so that the execution of the short previous-procedure itself is prevented. At this time, if registration of control information to storing means is prohibited, the modem parameter is stored, after which communication in the normal communication protocol is started. Therefore, a waste short previous-procedure in which the error occurs again is not executed.
The nineteen aspect of the present invention, in the data communication apparatus of the eighteen aspect, the apparatus further comprises parameter registering means for storing various kinds of the modem control information obtained in the normal previous-procedure, wherein prohibition of executing the short previous-procedure is carried out by prohibiting said various kinds of the modem control information from being written to said parameter registering means.
According to the above-mentioned structure, for example, the prohibition of various kinds of modem control information to storing means by parameter registration means based on software, thereby making it possible to prohibit the short previous-procedure from being executed easily.
The twenty aspect of the present invention, in the data communication apparatus of the first to fourth aspect, the apparatus further comprises operating means for changing a destination""s name stored in said storing means or a destination""s telephone number; and memory controlling means for automatically erasing all information of a relevant information storing area including modem control information stored in association with said destination""s telephone number when there is a change in said destination""s telephone number input by said operating means.
According to the above-mentioned structure, the parameter can be registered in association with a new destination""s telephone number. When the telephone number is changed, the line characteristic is also changed in many cases. However, control information can be erased and updated in a state that the operator has no awareness thereof. Control information to be erased here includes short previous-procedure registration prohibition information, that is, all information stored in association with the destination""s telephone number.
The twenty-one aspect of the present invention, in the data communication apparatus of the first to fourth aspect, the apparatus further comprises operating means for inputting an identification code peculiar to a self-apparatus; and memory controlling means for automatically erasing all information of a relevant information storing area including modem control information stored in association with all telephone numbers destination-registered when there is a change in said identification code input by said operating means.
According to the above-mentioned structure, when the telephone number of the self-apparatus is changed, all information including control information and short previous-procedure registration prohibition information can be automatically erased without executing the operation by the operator.
The twenty-two aspect of the present invention, the apparatus further comprises parameter registering means for storing various kinds of the modem control information obtained in a next normal previous-procedure executed with respect to a destination in said storing means in a state that only the destination corresponding to an operation key is stored in storing means. Thereby, the automatic registration of parameter can be executed with respect,to storing means in which control information has been automatically erased in next communication.
The twenty-three aspect of the present invention, the apparatus further comprises memory control means for automatically erasing all information of a relevant information storing area including modem control information stored in association with all telephone numbers destination-registered when an error continuously occurs in the short previous-procedure executed with respect to a plurality of destinations.
According to the above-mentioned structure, on the presumption that the reason why a continuous error occurs in the short previous-procedure lies in a change in the kind of line to which the self-apparatus is connected, the execution of the short previous-procedure can be prohibited. Therefore, in subsequent communication, the normal communication is sequentially executed, and new control information can be registered.
The twenty-four aspect of the present invention, in the data communication apparatus of the first to fourth aspect, said control information is deleted from said storing means after a lapse of a predetermined period of time from registration of control information to said storing means so as to execute an update of control information by parameter registering means.
According to the above-mentioned structure, modem control information to be registered in memory means can be maintained to an optimal state.
The twenty-five aspect of the present invention, in the data communication apparatus of the first to twenty-four aspect, the apparatus further comprises memory control means for rewriting the modem control information registered in said storing means, wherein every time when a normal previous-procedure is executed to acquire modem control information, said memory control means adds modem control information newly acquired, corrects the modem control information registered in said storing means so as to be recorded again.
According to the above-mentioned structure, since the parameter is corrected and learned for each communication so as to be maintained to be an optimal value, suitable communication having short communication time, high communication speed, and a low error rate can be carried out while using the short previous-procedure.
The twenty-six aspect of the present invention, in the data communication apparatus of the first to twenty-four aspect, suitable modem control information is calculated based on a plurality of modem control information obtained by repeating execution of a normal previous-procedure a plurality of times, and said calculated control information is registered in said storing means.
According to the above-mentioned structure, since initial registration of modem control information to be registered in storing means can be adjusted and registered, a probability of success of the short previous-procedure can be improved.